$8ef - 5eg - 9e + 9 = -6f + 4$ Solve for $e$.
Combine constant terms on the right. $8ef - 5eg - 9e + {9} = -6f + {4}$ $8ef - 5eg - 9e = -6f - {5}$ Notice that all the terms on the left-hand side of the equation have $e$ in them. $8{e}f - 5{e}g - 9{e} = -6f - 5$ Factor out the $e$ ${e} \cdot \left( 8f - 5g - 9 \right) = -6f - 5$ Isolate the $e$ $e \cdot \left( {8f - 5g - 9} \right) = -6f - 5$ $e = \dfrac{ -6f - 5 }{ {8f - 5g - 9} }$ We can simplify this by multiplying the top and bottom by $-1$. $e= \dfrac{6f + 5}{-8f + 5g + 9}$